<html>
<head>
<script>
  function launchFullscreen(element) {
    element.webkitRequestFullscreen();
  }

  function exitFullscreen() {
    document.webkitExitFullscreen();
  }
</script>
</head>
<body>
  <div>
    <button id="enter_fullscreen" onclick="launchFullscreen(document.documentElement);">Launch Fullscreen</button>
    <button id="exit_fullscreen" onclick="exitFullscreen();">Exit Fullscreen</button>
  </div>
</body>
</html>
